2014 college football rankings, Week 4: The composite Top 25

The bulk of college football's non-conference play is just about over, and the rankings will start to get just a bit clearer by the week. Four ranked teams lost in Week 3 (last week's composite No. 4 Georgia, No. 9 USC, No. 17 Virginia Tech, and No. 20 Louisville), hence the major shakeups this time around.

The four big rankings are out -- the two human polls and two long-running computer standings -- and we've combined them into one. See below for notes on these rankings:

The four rankings we use:

The Associated Press Top 25: The longest-running and best-respected human poll. Didn't have any official bearing on the latter years of the BCS, and won't have any official bearing on the Playoff. Expect it to set the course for the committee, however, as most outlets (including SB Nation) will use the AP's rankings as the standard until the committee takes over in October. Usually comes out Sundays around 2 p.m. ET.

The USA Today Coaches Poll: Formerly part of the BCS, and now just a poll. It tends to be more conservative than the AP's. Though polling athletic departments in order to rank other athletic departments is dubious, we still want multiple human polls in here, and it's the other big one. Releases early Sunday afternoons.

Jeff Sagarin's Sagarin Rating: An early-morning insta-ranking that combines three of Sagarin's computer formulas into one. This is not the formula the BCS used, which excluded margin of victory.

Football Outsiders' F/+ rating: A synthesis of ratings by smart persons Bill Connelly and Brian Fremeau and our personal go-to overall team stat. It tends to come out later than the others.

Last week's composite Top 25: